Tyranitar's Sand Stream hinders Dragonite's Multiscale ability, should it carry
that ability, so Dragonite isn't exactly the best choice to pair with Tyranitar.
While Garchomp is immune to sandstorm, Kingdra lets you check opposing rain
teams, so the choice is up to you, really.

I meant type-wise, which choice will give me more type coverage? Also, what about laying traps? Are none of these pokemon good for that? Additionally, if none of them are good for traps, I'm just going to start with dragonite to avoid that first problem, or simply send out Tyranitar after Dragonite faints, or teach Kingdra rain dance and have it be a weather-oriented pokemon